[Intel-gfx] [PATCH 58/62] drm/i915/bdw: Disable centroid pixel perf optimization

[Paulo Zanoni]

2013/11/3 Ben Widawsky <benjamin.widawsky at intel.com>:
> From: Ben Widawsky <ben at bwidawsk.net>
>
> BDW-A workaround
>
> BDW Bug #1899532
>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_reg.h | 3 +++
>  drivers/gpu/drm/i915/intel_pm.c | 2 ++
>  2 files changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 2d16363..8080a4d 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4986,6 +4986,9 @@
>  #define HSW_ROW_CHICKEN3               0xe49c
>  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
>
> +#define HALF_SLICE_CHICKEN3            0xe184
> +#define   GEN8_CENTROID_PIXEL_OPT_DIS  (1<<8)
> +
>  #define G4X_AUD_VID_DID                        (dev_priv->info->display_mmio_offset + 0x62020)
>  #define INTEL_AUDIO_DEVCL              0x808629FB
>  #define INTEL_AUDIO_DEVBLC             0x80862801
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index e6e12e1..dd0d375 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5286,6 +5286,8 @@ static void gen8_init_clock_gating(struct drm_device *dev)
>         I915_WRITE(WM2_LP_ILK, 0);
>         I915_WRITE(WM1_LP_ILK, 0);
>
> +       I915_WRITE(HALF_SLICE_CHICKEN3,
> +                  _MASKED_BIT_ENABLE(GEN8_CENTROID_PIXEL_OPT_DIS));

Shouldn't we add a comment saying this is, so far, only to
pre-production machines and we might want to remove this later?
Hunting down these things later won't be easy if we don't have nice
comments helping us. We all have seen many cases where WAs that apply
only to pre-production machines only get removed a long long time
after we should have removed.


>         I915_WRITE(GAMTARBMODE, _MASKED_BIT_ENABLE(ARB_MODE_BWGTLB_DISABLE));
>
>         /* WaSwitchSolVfFArbitrationPriority */
> --
> 1.8.4.2
>
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-- 
Paulo Zanoni